This proposal is directed toward an understanding of the factors which regulate the synthesis, release and functional effects of prostaglandins in the kidney, and their role in renal disease. Models to be studied include the isolated perfused rat kidney, and experimental and clinical examples of renal disease. We propose to study three main areas: 1) the interaction between prostaglandins and renin in the kidney, 2) the relationship between prostaglandins, heart failure, and requirements for sodium balance, and 3) the role of prostaglandins in renal diseases, with special reference to disorders of concentrating ability and to compensatory adjustments in renal insufficiency.